Having emacs commands by default on native apps is a really nice detail. It's nearly impossible to do on Windows since there's already a bunch of shortcuts using control. On Linux it's definitely doable but you have to install a keyboard shortcuts app, get an emacs profile, etc. If only reddit didn't use C-b to insert bold text, it'd make navigating in text boxes a lot easier.
I have to use a web application that uses CKEditor for text boxes.
And just like you - the most annoying thing in the world - j I get: control-b is bold instead of back one character (one of my most commonly used keystrokes)
The other annoying one is control-k pops up a link dialog.
I tried to figure out how to override or disable it, but never got very far.